Bi{11 O{11 {11 CONTAINING Pbo-Zno-B{11 O{11 {11 LOW TEMPERATURE SEALING GLASS

ABSTRACT

A family of sealing glasses which may be used for sealing glass plates together at relatively low temperatures. The glasses all have softening temperatures in the range 415*-428*C and have thermal coefficients of expansion (from room temperature to 300*C) in the range of 80-83 X 10 7 per *C. The glasses consist substantially of the following constituents in the following proportions: Per cent by weight PbO 60.5 - 64.0 B2O314.5 - 17.5 ZnO14.5 15.2 SiO2 1.0 - 3.0 CuO 3.0 - 4.5 Bi2O3 1.3 - 2.

United States Patent [191 Sherk et al. Oct. 15, 1974 [54 I Bi OCONTAINING PbO-ZnO-B O LOW 3,127,278 3/1964 Francel et a1 106/53TEMPERATURE SEALING GLASS 3,291,586 12/1966 Chapman et a1 106/53Inventors: Thomas A. Sherk, West Hurley; Rao R. Tummala, WappingersFalls,

both of NY.

International Business Machines Corporation, Armonk, NY.

Filed: July 31, 1973 Appl. No.: 384,314

Assignee:

US. Cl. 106/53, l06/54 int. Cl. C030 3/10, C030 3/12, (03c 3/30 Field ofSearch 106/47 R, 53

References Cited 1 UNITED STATES PATENTS 4/1960 Veres 106/53 1/1963Veres 106/53 Primary Examiner-Winston A. Douglas Assistant Examiner-MarkBell Attorney, Agent, or Firm-Edward S. Gershuny 5 7 ABSTRACT Percent byweight PbO .1 60.5--64.0 B 0 14.5--17.5 ZnO t 14.5-15.2 SiO 1,0 3.0 CuO3.0 4.5 Bi O, 1.3 2.5

6 Claims, No Drawings INTRODUCTION This invention relates to scalingglass compositions. More particularly, the invention relates to glasseswhich have a relatively low softening temperature and have a thermalcoefficient of expansion which makes them compatible withsoda-lime-silica substrates.

When manufacturing gas panel display devices, one step in themanufacturing process involves the use of a sealing glass to join twoprefabricated glass panels together in a fixed spacial relationship. Inorder to avoid the generation of conditions detrimental to theprefabricated panels, it is desirable that the sealing step be achievedat a relatively low temperature. It is also highly desirable that, asthe sealed panels are cooled, both the sealing glass and the glasssubstrates of the panels undergo substantially the same amount ofphysical contraction. This is desirable because unequal amounts ofcontraction would introduce stresses into' the sealed unit which couldeventually cause cracking of the glass.

SUMMARY OF THE INVENTION The sealing glasses of this invention consistessentially of the following ingredients in the following proportions:

These glasses have softening temperatures in the range 4l5420 C and TCEin the range 82.2 83.0 (from room temperature to 300C). The primaryadvantages of this invention are that the glasses can be used forsealing at relatively low temperatures and that the glasses have thermalcoefficients of expansion that are compatible with the prefabricatedpanels.

DETAILED DESCRIPTION All of the glasses described herein consistessentially of ingredients within the ranges shown in the followingtable.

Per cent by weight PbO 60.5 64.0

8 0. 14.5 17.5 ZnO 14.5 15.2 $10 1.0 3.0 CuO 3.0- 4.5 131,0, 1.3 2.5

Per Cent B y Weight I II III IV V PbO 6|.5 64.0 6L0 61.6 60.5 B 0 14.915.3 15.0 [4.5 l7.5 Z nO l4.5 l4.9 14.5 l5.2 l4.5 $10. 2.6 l.5 3.0 2.5L0 CuO 4.0 3.0 4.0 3.8 4.5 Bi O 2.5 1.3 2.5 2.4 2.0 TCE(RT-300) 82.283.0 80.5 8L0 80.0 TSoft 420 4l5 425 423 428 TSeal 465 460 470 460 470Per cent by weight PbO 60.5 64.0 13,0, 14.5 17.5 ZnO 14.5 15.2 $10 1.0-3.0 010 3.0- 4.5 131,0 1.3 2.5

responds to a TCE of approximately 80-84 in the temperature range fromroom temperature (approximately 22C) to 300C. Glasses which areespecially suitable for use in this process consist of essentially thefollowing ingredients in the following proportions:

Per cent by weight PbO 61.5 64.0 a.,o 14.9 15.3 ZnO 14.5 15.2 s10, 10-3.0 010 3.0- 81,0, 1.3 2.5

It will be noted that all of these glass compositions exhibit a TCEwhich is quite compatible with that of the glass substrate of theprefabricated panels. It is also of significance that, when using thesesealing glasses, the prefabricated panels can be sealed together ata temperature substantially below the crazing temperature of a magnesiumoxide overcoat (485-505C) that results when using any of the dielectricglasses described in examples I-IV of co-pending application Ser. No.374,189 filed June 27, 1973 for DIELECTRIC GLASS COMPOSITION. (Foradditional details of the process of manufacturing gas display panels,reference is made to copending application Ser. No. 214,348, filed Dec.20, 1971 for GAS PANEL FABRICATION by P. H. Haberland et al.)

As compared with sealing glasses known in the prior art, characteristicswhich particularly distinguish the glasses described above are: therelatively low range of lead oxide (PbO); the relatively high range ofzinc oxide (ZnO); and the addition of a relatively small but criticallyimportant amount of bismuth oxide (Bi O The latter ingredient is ofparticular importance with respect to achieving the low-expansion andlowsoftenin'g properties of these sealing glasses.

The five glasses described in the above examples are presented in whatis regarded as their order of suitability for use in the manufacture ofgas display panels. Example V. although it can be used satisfactorily,is substantially less desirable than any of the glasses described inexamples 1-1V primarily because its softening and sealing temperaturesare somewhat high and its TCE is somewhat low as compared to the otherglasses. The glasses described in example l-lV, all of which aresubstantially more desirable than the glass described in example V,consist essentially of the following ingredients in the followingproportions:

Per cent by weight PbO 61.0 54.0 13 0., 14.5 -15.3 ZnO 14.5 15.2 sio 1.53.0 CuO 3.0- 4.0 131 1.3 2.5

With respect primarily to the three critical parameters of softeningtemperature, sealing temperature, and TCE, the glasses described inexamples 1 and 11 are substantially more suitable for use in the processof manufacturing gas panel displays than any of the other glasses. Thesesealing glass compositions consist essentially of the followingingredients in the following proportions:

Per cent by weight PbO 61.5 64.0 B 0 14.9 15.3 ZnO 14.5 14.9 1.5 2.6 CuO3.() 4.0 Bi O 1.3 2.5

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that varoius changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

l. A sealing glass composition having a thermal coefficient of expansion(from room temperature to 300C) in a range of 8083 10 per C consistingessentially of the following ingredients in the following proport1ons:

Per cent by weight Lead oxide (PbO) 60.5 64.0 Boric oxide (B 0 14.5 17.5Zinc oxide (ZnOl 14.5 15.2 Silicon oxide (SiO- 1.0 3.0 Copper oxide(CuO) 3.0 4.5 Bismuth oxide (Bi o 1.3 2.5

2. A sealing glass composition having a thermal coefficient of expansion(from room temperature to 300C) in a range of -83Xl0 per C consistingessentially of the following ingredients in the following proport1ons:

Per cent by weight Lead oxide (PbO) 61.0 64.0 Boric oxide (B 0 14.5 15.3Zinc oxide (ZnO) 14.5 15.2 Silicon oxide (SiO 1.5 3.0 Copper oxide (CuO)3.0 4.0 Bismuth oxide (Bi O 1.3 2.5

3. The sealing glass composition of claim 2 wherein there is 14.9 15.3percent by weight B 0 and 14.5 14.9 percent by weight ZnO. 1

4. A sealing glass composition having a thermal coefficient of expansion(from room temperature to 300C) in a range of 8083 l0' per C consistingessentially of the following ingredients in the following proport1ons:

Per cent by weight Lead oxide (PbQ) 61.5 64.0 Boric oxide (B 0 14.9 15.3Zinc oxide .(ZnO) 14.5 14.9 Silicon oxide (SiO- 1.5 2.6 Copper oxide(CuO) 3.0 4.0 Bismuth oxide (1350 1.3 2.5

1. A SEALING GLASS COMPOSITION HAVING A THERMAL COEFFICIENT OF EXPANSION(FROM ROOM TEMPERATURE TO 300*C) IN A RANGE OF 80-83X10-**7 PER *CCONSISTING ESSENTIALLY OF THE FOLLOWING INGREDIENTS IN THE FOLLOWINGPROPORTIONS:
 2. A sealing glass composition having a thermal coefficientof expansion (from room temperature to 300*C) in a range of 80-83 X 10 7per *C consisting essentially of the following ingredients in thefollowing proportions:
 3. The sealing glass composition of claim 2wherein there is 14.9 - 15.3 percent by weight B2O3 and 14.5 - 14.9percent by weight ZnO.
 4. A sealing glass composition having a thermalcoefficient of expansion (from room temperature to 300*C) in a range of80-83 X 10 7 per *C consisting essentially of the following ingredientsin the following proportions:
 5. A sealing glass composition inaccordance with claim 4 consisting essentially of: 61.5 percent PbO,14.9 percent B2O3, 14.5 percent ZnO, 2.6 percent SiO2, 4.0 percent CuOand 2.5 percent Bi2O3.
 6. A sealing glass composition in accordance withclaim 4 consisting essentially of: 64.0 percent PbO, 15.3 percent B2O3,14.9 percent ZnO, 1.5 percent SiO2, 3.0 percent CuO and 1.3 percentBi2O3.